I have an 08 Malibu LSV with the Hammerhead engine. For the first year I had the boat I remember being able to hit about 43 MPH before the speed topped out, and no more speed was possible. No rev. limiter would ever kick in. I don't remember ever looking at how many revolutions the prop was spinning at though. This year, I can't seem to break about 37 MPH. The difference is what I guess can only be the rev. limiter kicks in right about 4800 RPM (or 48000, whichever makes sense). I don't have my owners manual with me and I can't figure out what the rev. limiter is set at or even if my boat has one? The reason I think its the rev. limiter is simply because right at the same point, the engine quickly and breifly drops power, and the RPS drop slightly. It takes about 2 to 3 seconds to bring it back up, but feels exactly like a speed governor in a car.

It could be your prop key slipping, allowing the motor to hit the rev limiter without the boat hitting top speed. Check that first and see. If you prop key slips, your prop will not spin as fast as the shaft so the motor is turning more rpm than the prop, thus the lower top speed and higher motor speed and hitting the rev limiter. Good luck.

5250 rpm is where the rev limiter should kick in on that motor. With the stock ACME 537 prop you will only be able to hit rev limiter in ideal conditions. If you're hitting it at 4800 rpm something is wrong and your dealer needs to take a look at it.

Nu Bu, 5250 would make sense that was what it should be. I remember getting a software upgrade last year. Could that have changed something?

Check your spark plugs, most dealers are going away from the delco plugs that are gapped at .065 and going to NGK gapped to .045 instead. This is eliminating alot of those plug issues they
ve been having.

Maybe they loaded the wrong program in your boat when they updated it?